Conventionally, a vehicle is equipped with a pedestrian protection device for reducing an impact to a pedestrian in case where the pedestrian collides with the vehicle. The vehicle has a collision detection device including a sensor that is disposed in a bumper of the vehicle. When the sensor detects that a pedestrian collides with the vehicle, the pedestrian protection device is operated to reduce the impact applied to the pedestrian. A pop-up hood is one of the pedestrian protection devices. When a collision is detected, the pop-up hood raises the back end of an engine hood so as to increase the interval between the pedestrian and hard parts such as engine. The collision energy to a head of the pedestrian is absorbed using the space, such that the impact to the head of the pedestrian is reduced.
A collision detection device for a vehicle has a chamber component defining a chamber space inside, and the chamber component is arranged on the front surface of a bumper reinforcement in a bumper of the vehicle. A pressure in the chamber space is detected with a pressure sensor. If an object such as pedestrian collides to the bumper (bumper cover), the chamber component is deformed by a deformation of the bumper cover, and a pressure variation is generated in the chamber space. The pressure variation is detected by the pressure sensor such that the collision of the object to the bumper can be detected.
Recently, a tube-type collision detection device for a vehicle is proposed, which detects a collision using a tube component that is small and easy to handle, compared with the chamber-type collision detection device. The collision detection device includes a bumper absorber arranged in the bumper, a hollow tube component mounted to a groove portion defined in the bumper absorber to extend in the vehicle width direction, and a pressure sensor that detects a pressure variation in the tube component. When a pedestrian collides with a front of a vehicle, the bumper absorber deforms and absorbs the impact, and the tube component deforms at the same time. At this time, the pressure in the tube component is raised, and the pressure change is detected by the pressure sensor, such that a collision of the pedestrian to the vehicle can be detected.